08Chat-app style bubble

<main class="stage">
  <div class="chat-wrap">
    <div class="avatar" aria-hidden="true">AI</div>
    <p class="bubble is-demo" role="status">Hi! How can I help?</p>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

$duration: $dur-loop;                              // 숨김→표시→숨김 한 주기
$easing: $ease-pop;                                // 등장 바운스
$color: $subject-blue;                             // 말풍선 색

@include stage($stage-paper);

.chat-wrap {
  display: flex;
  align-items: flex-end;
  gap: 10px;
}

.avatar {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: $stage-ink;
  color: #fff;
  font-weight: 700;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  flex: none;
}

.bubble {
  position: relative;
  margin: 0;
  max-width: clamp(160px, 46vw, 240px);
  background: $color;
  color: #fff;
  padding: 12px 16px;
  border-radius: 18px 18px 18px 4px;               // 왼쪽 아래만 각져 꼬리처럼 보인다
  font-size: clamp(12px, 3.4vw, 14px);
  opacity: 0;
  transform-origin: bottom left; // 규칙8: 꼬리 bottom left 고정 팝
  transform: scale(.85);

  &::after {                                        // 말풍선 꼬리
    content: "";
    position: absolute;
    left: -6px;
    bottom: 0;
    width: 12px;
    height: 12px;
    background: $color;
    clip-path: polygon(100% 0, 100% 100%, 0 100%);
  }
}

.bubble.is-demo {
  animation: bubble-loop $duration $easing infinite;
}

// 등장 스프링 한 겹 — 스케일 .85 → 1.14 오버슛 → 감쇠 반동(.93 → 1.02), 회전은 꼬리 축(bottom left)으로 3° → -1.7° → .7° 감쇠
@keyframes bubble-loop {
  0%       { opacity: 0; transform: scale(.85) rotate(0deg); }
  12%      { opacity: 1; transform: scale(1.14) rotate(3deg); }
  22%      { opacity: 1; transform: scale(.93) rotate(-1.7deg); }
  30%      { opacity: 1; transform: scale(1.02) rotate(.7deg); }
  36%, 55% { opacity: 1; transform: scale(1) rotate(0deg); }
  80%      { opacity: 0; transform: scale(.85) rotate(0deg); }
  100%     { opacity: 0; transform: scale(.85) rotate(0deg); }
}

@media (prefers-reduced-motion: reduce) {
  .bubble.is-demo { animation: none; opacity: 1; transform: scale(1) rotate(0deg); }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.chat-wrap {
  display: flex;
  align-items: flex-end;
  gap: 10px;
}

.avatar {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: #17141a;
  color: #fff;
  font-weight: 700;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  flex: none;
}

.bubble {
  position: relative;
  margin: 0;
  max-width: clamp(160px, 46vw, 240px);
  background: #2f6df6;
  color: #fff;
  padding: 12px 16px;
  border-radius: 18px 18px 18px 4px;
  font-size: clamp(12px, 3.4vw, 14px);
  opacity: 0;
  transform-origin: bottom left;
  transform: scale(0.85);
}
.bubble::after {
  content: "";
  position: absolute;
  left: -6px;
  bottom: 0;
  width: 12px;
  height: 12px;
  background: #2f6df6;
  clip-path: polygon(100% 0, 100% 100%, 0 100%);
}

.bubble.is-demo {
  animation: bubble-loop 2s cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

@keyframes bubble-loop {
  0% {
    opacity: 0;
    transform: scale(0.85) rotate(0deg);
  }
  12% {
    opacity: 1;
    transform: scale(1.14) rotate(3deg);
  }
  22% {
    opacity: 1;
    transform: scale(0.93) rotate(-1.7deg);
  }
  30% {
    opacity: 1;
    transform: scale(1.02) rotate(0.7deg);
  }
  36%, 55% {
    opacity: 1;
    transform: scale(1) rotate(0deg);
  }
  80% {
    opacity: 0;
    transform: scale(0.85) rotate(0deg);
  }
  100% {
    opacity: 0;
    transform: scale(0.85) rotate(0deg);
  }
}
@media (prefers-reduced-motion: reduce) {
  .bubble.is-demo {
    animation: none;
    opacity: 1;
    transform: scale(1) rotate(0deg);
  }
}

import { useEffect, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./ChatBubble.module.scss";

export type ChatBubbleProps = {
  avatar: string;
  text: string;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function ChatBubble({
  avatar,
  text,
  duration = 260,
  easing = "cubic-bezier(.2,1.4,.4,1)",
  color = "#2f6df6",
}: ChatBubbleProps) {
  const [shown, setShown] = useState(false);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  // 마운트되면 한 번 등장한다 — 채팅창에 메시지가 도착하는 흐름
  useEffect(() => {
    const t = setTimeout(() => setShown(true), 60);
    return () => clearTimeout(t);
  }, []);

  return (
    <span className={styles.wrap} style={vars}>
      <span className={styles.avatar} aria-hidden="true">{avatar}</span>
      <p className={styles.bubble} data-open={shown}>{text}</p>
    </span>
  );
}